Im not really sure about this but somone i talked to said i might need to change over from speed density to MAF to make my engine run, i just finished a swap and im having a real tough time getting the damn thing to run good. I was told that the cam may be too wild for the stock tpi computer, but i really dont know too much about tpi, I mean it runs now but really really rough, i even took it to a f-body shop and the mech. there nad tons of problems getting it to run, but he did burn me a chip with altered values, for my 32# injectors and such, but here's whats in the engine

355 .030 over 9.1 compression
AFR 195 heads
Comp Camps roller grind for blower specs:
276 intake
290 exhaust
220 at .050
230 at .050
510 intake with 1.5 rocker
510 exhaust with 1.5 rocker
114 lobe
Crane aluminum rockers 1.6 ratio
TRW blower pistons
Total seal rings
Eagle Sir Rods 5.7
GM 1053 steel crank
Moroso 6 qt pan
High volume pump and pickup.
Fluidamper and tci flywheel both sfi approved
Edelbrock aluminum water pump for TPI serpintine
Accel 32# injectors
Stock ignition
Edelbrock TES headders
52MM TB, mildly ported TPI unit, mostly by the throttle blades.

Do i need to switch to MAF, how much might this cost, or is there another reason the engine may not be running the way it should, maybe i need to get a AFPR ? or somthing. Anyway any insight would be very very helpful.

 

Switch to maf to make it work? Thats the silliest thing I ever heard....

Someone should be able to sell/burn you a prom to work pretty decent with that setup on a sd setup. I wouldnt even think about swapping to maf to 'solve' the problem because even though it may run ever so slightly better, its still going to be far from right. Getting a custom chip from someone like Fastchips would cost around the same if not less than going through the hassle of swapping over the ecm and related sensors.

 

I agree with Madmax. I know guys (Traxion for example) that run a much wilder cam on SD with no problems. Yes it took a while to tune, but it can certainly be done.

In fact, when you get into really big cams, a lot of guys switch from MAF to SD, not the other way around. Yes, MAF is not affected as much by the lower vacuum readings, but the reversion through the MAF causes more havoc and cannot be "tuned out".

The low vacuum readings of a large cam can be "tuned" with SD. Though the guys that burn their own eproms have the best luck.

But since you can't/won't burn your own eproms, then going to someone like Ed Wright is your next best alternative. However, to get the "best results" from a custom eprom writer, you generally need to get "scan tool" readings to the writer for them to analyze what's going on and how to correct it.

 

in the slitest chance you would be interested in a maf tpi, i would be willing to trade you my maf tpi setup out of my 87 in my sig for your speed density .

thanks
anthony

 

Hell, it's simpler than that. Just grab a 7730 out of a wrecking yard (they are a dime a dozen). Re-pin the wires in the 165 connectors to the 7730 style connectors, re-wire the leads to the MAF to the MAP sensor, splice the MAP sensor into the MAF wires...and get a SD Memcal.

You can chose where you wish to convert to the SD style of Knock Sensor or re-use it. I prefer to use the SD style, it makes it a "complete" conversion and when youi are finished it will look like your car came with SD from the factory (except the spliced MAP sensor into the MAF wires).

 

i new i could repin this because my freind momar has 7730 siting in his room and was planning on doing that until he sold his tpi setup because he just would rather start out with a sd tpi setup. i was just seeing if hell would freeze over and he would be willing to trade me, the 87 tpi i have is an extra tpi setup i have, and am considering simeesing (sp) the intake and runners and porting everything possible to see what kind of gains i can get out of it. anyway, i doubt that hell will freeze over anytime soon

thanks
anthony

 

The first thing that jumped out at me was the huge injectors you're running...30# is a lot o' gas. What is your injector flowrate constant set to?

If you can get some ALDL data while it's running that will guide you on where it needs tuning...from initial startup while it's warming up in open loop mode you're watching the O2 sensor output voltage.

I like to warm mine up at ~600-700mV as reported by the O2 sensor, and you adjust this in the "Open Loop Air:Fuel Versus Coolant Temp" table. Higher numbers = more fuel per unit volume air which will richen things up, lower numbers = less fuel and leaner burn.

After you get the thing to idle in open loop, you can warm it up to transition to closed loop and start VE tuning and spark tuning. There's a great article by TRAXXION (not the PROM burning one, the non-PE one) on this. VEMaster might help, do a search...basically just drive the car at part-throttle, no WOT, with DataMaster capturing data. You then run VEMaster against this captured data and the .BIN file you were running, it will mathematically adjust your VE tables. Takes a few passes, and afterward there may still be some additional efficiency to be found by manually tweaking the VE tables.

You're also watching for spark knock counter to increment, or see the retard number >0. This tells you where to adjust the main spark tables.

After that, I usually hit the dragstrip for some WOT data captures and tuning. VEMaster won't help here, just gotta watch the O2 sensor output and spark knock/retard data and adjust PE fueling and spark.